Percent Grade 
To evaluate the proposed slope of a driveway, road, etc. a calculation is done by dividing the rise and fall of the grade by the distance over which the rise and fall is measured. This decimal figure is then multiplied by 100 to obtain the percent grade. 

Percentage of Completion Method 
Recognizes profit on a long-term construction contract as it is earned gradually during the construction period. This approach is referred over the completed contract method because it does a better job of matching revenue and expense in the period of benefit. It should be used when reliable estimates of the degree of completion are possible. It is more realistic and levels out the earnings. 

Percentage of Monthly Gross Income Rule 
Rule stating that the monthly mortgage payment, property taxes and insurance should not exceed 25% of a family's monthly gross income, or about 35% for a Federal Housing Administration (FHA) or Veterans Administration (VA) mortgage. 

Percentage Lease 
A lease of property in which the rental is based on a percentage of the volume of sales made upon the leased premises. It usually stipulates a minimum rental and is regularly used for retailers who are tenants. 

Percentage Rent
Rent payable under a percentage lease. Typically the percentage applies to sales in excess of a pre-established base amount of the dollar sales volume. 

Per-diem Interest 
Amount of interest due each day. 

Perch 
1. Land surveying measurement that is 16.5 feet in length, or 5½ yards. A perch is also called a rod or a pole. Today the term perch is seldom used: however, it is found in old deeds, surveys, and contracts.
2. Stone measurement equal to 16 ½ x 1 ½ x 1 ft, which is 24 ¾ cubic feet, used for stone stair steps. 

Percolate 
To pass a liquid gradually through small spaces or a porous substance. 

Percolation Test 
Test which is used to determine how well soil will accommodate a septic system, by judging how well liquid passes through the soil. Commonly referred to as a "perc test". 

Percussion Welding 
Electric resistance welding, usable on small flat surfaces, where the electrical current is passed, rapidly between the pieces to be welded, to heat them to the needed temperature, with the rapid force being applied during or directly after the electrical current to bond the surface with only a thin layer of bond. 

Perennial
Plant that blooms actively throughout the entire year or blooms year after year. 

Perfboard
Sheet of compressed fiberboard that has small, evenly spaced holes for pegs, hooks or hangers and is used to store tools, etc. 

Perforated
Pierced with holes, often in a pattern or in a row to ease tearing. 

Perforated Metal Pipe 
The equally spaced holes, drilled in rows along the length of this pipe, make it useful for aeration in a tank of fluid. When placed at the bottom of the tank, the air that passes into the liquid from the pipe oxygenates and mixes the fluid in the tank. 

Performance 
In contract law, the completion of duties and obligations specified in a contract. 

Performance Bond 
A bond, also known as a completion bond, given by a contractor and issued by an insurance company to guarantee the completion of contracted work. Public authorities often require a performance bond prior to granting a contract for work to be completed. These bonds are usually issued by insurance companies. 

Pergola
1. An arbor with an open roof of cross rafters supported on posts or columns. It is usually covered with roses or vines. 
2. Column mounted horizontal trellis, which is an overhead covering for an outdoor structure. 

Perimeter
Outer property boundaries. Outside dimensions of a building. 

Perimeter Drain 
Drain that goes around the outside of a foundation to deter excess water. 

Perimeter Ducting 
HVAC ducting that runs within the outside exterior walls of a building. 

Perimeter Foundation 
Section of a building, on which the balance of the building rests, and which is in contact with the earth. This foundation covers only the outer dimensions of the building, unlike a slab foundation which runs under the entire building, and is usually constructed of steel bar reinforced concrete. 

Perimeter Heating 
Warm air heating system where ducts are located in the concrete slab of a building constructed without a basement. As the name implies, a perimeter heating system is located around the perimeter of the rooms of a building were the heated air from the furnace is carried through the ducts to registers located in the floor. The air is recycled through ceiling ducts back to the furnace. 

Perimeter Heat Loss 
Loss of heat that occurs through the outside building surfaces, which are exposed to the elements. Adequate insulation, windows and doors are helpful in controlling this loss. 

Perimeter Installation 
Warm air heating system where ducts are located in the concrete slab of a building constructed without a basement and within the outer walls of a building. As the name implies, a perimeter heating system is located around the perimeter of the rooms of a building were the heated air from the furnace is carried through the ducts to registers located in the floor. The air is recycled through ceiling ducts back to the furnace. 

Periodic Estate 
Tenancy from month to month or year to year, with no written lease, it is also known as periodic tenancy or tenancy at will. 

Periodic Tenancy 
Tenancy from month to month or year to year, with no written lease, it is also known as periodic estate or tenancy at will. 

Periphery
An outside surface. An outer boundary. 

Perjury
The giving of false statements under oath, which is a criminal act and punishable by imprisonment and fine. 

Perlite
Glassy volcanic rock with a pearly luster, which shows many concentric circular cracks. A lightweight expanded mineral products, it is used in insulation, concrete and plaster.